This invention relates to an adjusting device for adjustable rotor vanes, particularly vanes of a propeller pump or a turbine, having a machine shaft which is provided with a hub with the rotor vanes and which is associated with a first gear wheel, an adjusting shaft which is provided with a second gear wheel and which is arranged coaxially to the machine shaft, a transmission through which a relative rotation can be introduced between the adjusting shaft and the machine shaft, a first braking device for braking the adjusting shaft with respect to the rotating machine shaft and for adjusting the rotor vanes in a first direction, and a second braking device for effecting through said transmission an adjustment of the rotor vanes in a second direction opposite said first direction.
An adjusting device of this general type is known from German Pat. DE-PS No. 897,904, the transmission of which is arranged directly adjacent the hub. The hub is arranged at the end of the massively formed, solid machine shaft, and the transmission as well as the two braking devices are disposed on the side of the hub which faces away from the machine shaft. Supplemental measures must be taken so that the transmission and the braking devices are protected from the flowing medium in the vicinity of the hub. This results in problems with respect to assembly and service, primarily because in pumps or turbines the flow channel and the vicinity of the hub are not necessarily accessible. The transmission is constructed as a differential transmission and contains a bevel gear which is in engagement with the gear wheels which are connected with the machine shaft or with the adjusting shaft. A shaft arranged orthogonally to the machine shaft is connected with this bevel gear, and through this shaft, when one of the braking devices is actuated, the relative rotation is effected through further gear wheels for adjusting the rotor vanes. Because of the arrangement of this shaft and of the transmission on the side of the hub facing away from the machine shaft, this type of adjusting device cannot be readily included in machines in which the hub is arranged at one end of the machine shaft and the adjusting transmission is arranged at the other end of the machine shaft. Further, as a result of frictional effects and the consequent braking effects, relative rotations may occur which can lead to undesired adjustments of the rotor vanes.
An adjusting device for rotor vanes in which the hub with the rotor vanes is arranged at one end of the machine shaft and the transmission is arranged at the other end of the machine shaft is known from West German Published Application DE-OS No. 34 26 967. The machine shaft is constructed as a hollow shaft through which the adjusting shaft extends from the transmission to the hub. A tooth gear is fixedly connected with each of the machine shaft and the adjusting shaft, and the transmission is constructed as a planetary transmission, the drive shaft of which can be selectively turned in one or the other direction by an electric drive motor to adjust the rotor vanes. A consequent expenditure is required for the electric drive motor and its coupling to the transmission as well as the gear wheels, and additional energy must be supplied to effect an adjustment. In turbines there is a requirement that when the load is removed, the rotor vanes must be quickly brought into the sail position in order to prevent any unacceptable running away of the turbine. Since in this known device the transmission is arranged at the other end of the machine shaft from the hub, the adjusting shaft has a relatively large moment of inertia, and in order to make a sufficiently rapid adjustment of the vanes possible, a strong drive motor must be provided. Further, supplemental measures must be undertaken in order to avoid damage to the vanes or adjusting mechanism at high adjusting moments.